Secondary-clock mechanism.



C; M. CROOK.

SECONDARY CLOCK MECHANISM APPLICATION FILED APR.9. 1914.

1,280,171; Patented Oct. 1, 1918.

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C. M. CROOK.

SECONDARY CLOCK MECHANISM APPLICATION FILED mm. 1914.

1,280,171. 1 1 I Patented Oct. 1, 1918.

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'C. M. CROOK;

SECONDARY CLOCK MECHANISM APPLICATION HLED APR. 9.1914.

1,280,171. I v Patented O0t.1,'1918.

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MIL/ 255512 5 dropping back due to its own weight. Simi- UNITED STATES PATENT OFFICE.

CHARLES MADISON CROOK, OF CHICAGO, ILLINOIS, ASSIGNOR TO STROMBIIRG ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A' CORPORATION OF 'MAINE.

SECONDARY-CLOCK MECHANISM.

Specification of Letter Patent.

Patented Oct. 1, 1918.

Application filed April 9, 1914. Serial No. 830,690.

ful Improvements in Secondary-Clock Mech:

anism, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

' My invention relates to improvements in secondary clock mechanisms. x In secondary clocksas heretofore known it has been found that the minute hand in its upward course very often loses one or more minutes by larly on its downward course its weight" causes it todrop forward and to gain one or sible to be sure that the clock is registering the correct time, I

It is one of the principal objects of my invention to overcome these objections by locking the minute hand so that it cannot move except when properly moved forward by the clock mechanism.

his a further object of my invention to rovide. suitable means for efliciently lock-- mg the escapement so that the clock hands will be moved forward the proper distance and only the proper distance and only at the proper time.

Additional objects of my invention are to provide means for easily setting the clock when necessary; to provide a secondary clock having a simple structure so arranged that all of the parts are readily accessible for the purpose of inspection, oiling or repairs; andto provide a secondary clock mechanism which is simple and eflicient in its operation and economical to manufacture.

Further objects and advantages of my in-.

vention will be apparent from the following description taken in connection with the V appended claims. I I

I have described in the following specification and illustrated in the accompanying drawings a secondary clock mechanism-sing bodying my invention, by way of example, it being clearly understood that numerous changes may be made in the form, construction and arrangement of the parts without 'which'carries the operating me departin'gfrom the spirit of my invention or exceeding the scope of the appended claims, the form of the invention herein disclosed being merely one preferred embodiment thereo In the drawings: v

Figure 1 is a side elevation of a secondary clock mechanism constructed in accordance with my invention, showing the same secured to the door of a clock; A

'Fig. 2 is a detailed perspective, on a larger scale,- showing partofthe base;

. Fig.3 is a perspective showin the frame anism- Flg; 4 is a similar view showing part of the operating mechanism removed from the frame;

Fig. 5 is an enlarged cross-sectional view the line 55 of Fig. 6 ,looking in the direction of the arrows Fig, 6 is a similarf'view taken on the line 66 of Fig. 5 lookingin the direction of the arrows; .Fig. 7 1s a simllar view taken on the line 77 of Fig. 5, looking invthe direction of the direction of the arrows; and

7o of the device as shown in Fig. 1 removed from the door, the section being taken on.

V Fig. 9 is a view in rear elevation reduced. 1

Like reference characters refer to like parts throughout the following description and the several figures of thedrawings.

The embodiment of the invention illustrated comprises a secondary clock mecha nism of the sort in which'an electromagnet is connected to a master-clockwhich is arranged to cause the magnet to be energized once every minute for the purpose of rotating the hands of the clock. Theclock is provided with a suitable door 10 having the usual opening 11 in which a glass 12 is held with a split'ring 13 or other suitable means.

The clock face '14 is mounted at the rearof this opening and is secured to the front of an upright 15 mounted on theback of the door and which not only serves as a support for the clock face, but also as a support for the driving mechanism of the clock, which mechanism is bodily mounted upon this support 15; The operating mechanism of the clock comprises in general threeparts; the base, the frame and the operating mecha nism, including a pairv of electromagnets. The base 16 comprises a rectangular casting having a center opening'through which the clockstem may project and is secured to the upright 15 by a plurality, preferably four, of screws which pass through the strip from the front and engage in suitable screwthreaded openings at the fourcorners of the base. Extending rearwardly' from thebase, at its top and bottom, are a pair of parallel flanges 17 which form a groove for the receptlon ofthe rods 18 of the frame. There are two of these rods, one at the top and bottom of the frame, which are secured between the side plates 19 and 20, comprising a portion of the frame, by means of screws 21. These rods are arranged in the grooves formed between the flan es 17 and are locked in position by means 0 screws 22 adapted to pass through the base, the heads of the.

screws being arranged to engage in a central groove on the rods and being adapted to be countersunk in bushings 23 formed on the receptive top and bottom flanges on the base. The driving mechanism of the clock is mounted in the frame formed by the two side plates and a pair of front and back members 24. These two members are the same in construction and lie in suitable recesses formed in the edges of the two side members, being clamped in position by mean of rods 25 which, at their rear ends, are riveted to the back member, and, at their front end,"are adapted to receive screws 26 which pass through the front member. The

stem 27 of the clock, the front end of which is adapted to project through the dial and receive the minute hand 28, (mounted rigidly thereon), is mounted between the front and back members and has, rotatablymounted thereon, a sleeve 29, which sleeve also projects through the dial and is adapted to receive the hour hand 30. This sleeve is driven from the minute hand stem by means of a reducing gear comprising a pinion 31 mounted on the stem, and adapted to mesh' with the gear wheel 32 mounted upon, and rotating with, a shaft 33 secured between a pair of downwardly extending tugs 34 formed on the back and front memers.

This shaft also carries a pinion 35 rigidly connected with the gear and meshing with a gear 36 mounted upon the sleeve carrying the hour hand. The reducing gear thus described operates to cause the hour hand to make one revolution while the minute hand is making twelve. The minute hand stem is driven and operated from an intermittently rotating shaft 37 mounted between the two side members and'carrying a worm gear 38 adapted to mesh with a pinion 39 mounted directly upon the minute vents any slippage on the part of the mechanism of the clock, and also prevents the weight of the hands from causing the mechanism to skip.

The worm gear shaft is rotated once every minute by a pawl and ratchet mechanism, operated by an electromagnet energized from the master-clock once every minute. The ratchet wheel 40 of this pawl and ratchet mechanism is rigidly mounted upon the worm gear shaft and is adapted to be engaged by a pawl 41 comprising a pair of spaced-apart arm pivoted at 42 upon the end of a rocking arm 43. The forward spacing member 44 of these two arms provides the engaging member ofthe pawl which is adapted to engage the teeth of the ratchet wheel, and this pawl is held into engaging position with the ratchet teeth means of a coiled spring 45, one end of which is connected to the pawl and the other end of which is connected to a second backlash pawl 46, adapted to engage theratchet teeth of the wheel on its under side to prevent backlash of the ratchet wheel. Thi pawl is'pivoted to one side of the frame as illustrated. 3

The rocking arm 43 is provided, at its bottom, with a rearwardly extending arm 47 and the two arms, in effect, provide a bell crank lever being mounted upon a cross bar 48 secured between the two side members of the frame. The pivotal mounting of this bell crank lever is about central of the lower laterally extending arm 47, so that the arm will have a free rocking movement. At the pivotal point the arm is rigidly secured to a sleeve surrounding the rod 48 and on the opposite end of the sleeve is a second arm the armature from sticking to the ends of the pole pieces of the electromagnet. The armature lies in a position between a pair ofrearwardly extending arms 53-01 the side plates and the bottom'of the electromagnet, which electromagnet .comprises a pair of independently mounted spools of wire 54, 55 suitably wound on iron cores. The cores of each of the magnets are supported in position from a cross Member 56 secured upon a pair of rearwardly extending arms 57 of the side plates of the frame, by means of screws 58 which pass through the-- cross "member, through an iron bridging member 59, against which bridgihg member the pole pieces are clamped by the screws, and into the armature. is attracted by the electromagnet.

The electromagnet attracts its armature once every minute, and, 1n attracting. its

, armature, the arm 43'i caused to rock on wardly, thus placing under tension a coiled spring 6Q; one end of which is secured to a pin 61 projectingfrom the side pf the frame. The other end of the spring issecuredto a. pin 62 extending laterally from the lower end of the rocking arm {3 and passing through a suitable opening in the side frame. c

When the electromagnetis deenergized the coiled spring; causes the rocking arm 43 to make return movement so as to rotate the ratchet one notch, thereby 3 operating the clock" and moving the minute hand one minute. A post 63 bn one of the side plates of the frame serves as a stop to limit the out- Ward movement of the rocking arm and a similarstop 6'4: limits its return stroke, Con sequently its effective stroke is just suflicient to rotate the ratchet the proper distance to cause the minute hand to be. advanced one i Means are provided also for preventing any movementiof the ratchet other than its pro er advance movement, as above desc'ri ed. When the arm 43 reaches the 1im1t of its return or operating movement it en gagesthe stop 64 and becomes wedged be.- tween'this stop and the ratchet, whereby further rotation of the ratchet in a forward direction isprevented. As backlash is prevented by the springpressed pawl. 46, the ratchet is effectually locked against rotation in either direction except during the interval it is being driven forward by the operating pawl. p

When it is necessary to setthe clock, the hour hand is manually rotated about its sleeve to its correct position and the minute hand is advanced by means of a small wire handle 65 securedto the arm 43,- a pull on the handle rocking the arm in the same manner as when caused by the influence of the magnet. g g It will be noted, by" the above construction, first, that the clock mechanism, including the base and the operating parts, constitutes aunitary device which, in itself, may'be readily mounted upon a su porting member. It will also be noted that tl ie frameiwhich-is secured to the base, and on which'all of the operating parts of the clock are mounted,

also comprises a unitary structure which may be disconnected and removed from the base without'removing the base, if so desired. It will also be noted that the driving gear and the operating pawl and ratchet mechanism are mounted between the base and the electromagnet', the electroma'gnet be ing mounted at the rear of the frame and the two spools being readily removable from the frame independently of one another'to permit access to the mechanism of the clock for the purpose of oiling, repair, etc, It will also be noted thatit i not even necessary to remove vboth magnetsfor access to the driving trains, etc. ,.-as each magnet is removable independently of the other, and, therefore,

only one mlagnet need be removed if access is only desired atone side of the clock. The

whole mechanism is simple, readily assembled and disassembled, and, at the same time, provides an efficient secondary cloc'k mechanism having means for positively locking the hands thereof against movement except .the movement imparted thereto by the electromagnet and itsassociate parts.

Having disclosed my invention what I claim'as new and desire to secure by Letters Batent, is:

1. In a seconda'ry clock, a member having J a dial opening therein, a supporting bar extending across said opening, a base detachably secured thereto, frame detachably secured tosaid base, aclock hand, a shaftlon 'which said hand is secured, supported by said frame, and electromagnetic actuating mechanism for rotating saidshaft also carried by said" frame, said frame having horizontal rods. lying in/a plane substantially parallel to the plane of saidv first member and said base havingrecesses'to receive said rods. v

2.v The combination with a frame com pris ing rearwardly entending arms at the top,- clock hand operatlng mechanismwithin said frame between said side members, electro- 7 ing a pair of spaced apart, side members havmagnets for operating said mechanism supported from said arms behind said mechanlsm, and an armature at the bottom of the frame.

3. The combination witha face plate having top and bottom grooves in the rear face thereof, of a clock operating mechanism frame having a .pair of cross rods adapted to fit in v said grooves, and locking means for locking the cross rods in saidgrooves.

4. The-combination with a frame comprising a pair of spaced apart side plates having rearwardly extending arms atthe top, clock mechanism supported within said frame, a

driving ratchet Wheel supported within the frame near one of the side pieces, a bell crank lever mounted in the lower end of said wardly along one of said side pieces and c!"- rying at its end a pawl for operating the In witness whereof, I have hereunto subratchet wheel, the. opposite armextending scribed my name in the presence of two witsubstantially horizontally and carrying an nes'ses. v 1

ermature, and an electromagnet sup orted CHARLES MADISONCROOK. 5 at its upper end from said rearwar 1y ex- Witnesses:

tending arms and having the ends of its H. MONROE HUMASON,

cores in close proximity to the armature. ANNE SOLOMON, 

